基于陶瓷材料动态断裂韧性的测试方法研究

Research on Testing Method Based on Dynamic Fracture Toughness of Ceramic Materials

陶瓷材料的断裂方式为脆性断裂,其裂纹敏感性非常强,一般难以在T/Tm≤0.5的温度范围内发生塑性变形,断裂韧性是评价陶瓷材料韧性最主要的断裂力学参数。为研究陶瓷的动态断裂韧性,该文依据霍普金森压杆(Hopkinson)压杆实验原理,使用改进后的Hopkinson工具,对加工成形的单边切口梁陶瓷试件实施三点弯曲动态试验。改进型Hopkinson压杆装置用于测得透射应力波,以便于获得试件在变形中受到的支反力。文章从介绍Hopkinson测试原理和工具入手,在实验中分别研究了3种陶瓷材料的静态力学性能和静态断裂韧性,时间-动态应力强度因子曲线(kId-t)及其动态断裂韧性kIdC。最终测试结果显示陶瓷材料的动态断裂韧性对挠度变化率也较大依赖性。

The fracture mode of ceramic materials is brittle fracture, and its crack sensitivity is very strong. It is generally difficult to produce plastic deformation in the temperature range of T/TM≤ 0.5. Fracture toughness is the main fracture mechanics parameter to evaluate the toughness of ceramic materials. In order to study the dynamic fracture toughness of ceramics, based on the experimental principle of Hopkinson pressure bar, the three-point bending dynamic test of ceramic specimens with single notched beam is carried out by using the improved Hopkinson tool. The improved Hopkinson compression bar device is used to measure the transmitted stress wave, so as to obtain the support reaction force of the specimen in deformation. Starting with the introduction of Hopkinson test principle and tools, the static mechanical properties and static fracture toughness of three ceramic materials were studied in the experiment, Time dynamic stress intensity factor curve(kId-t) and its dynamic fracture toughness kIdC. The final test results show that the dynamic fracture toughness of ceramic materials also depends on the deflection change rate.